exec and globals and locals ...

[jfong at ms4.hinet.net]

>>> x = 3
>>> def foo():
...     exec("print(globals(), locals()); x = x + 1; print(globals(), locals())")
...
>>> foo()
{'foo': <function foo at 0x021C3468>, '__package__': None, '__builtins__': <module 'builtins' (built-in)>, '__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__doc__': None, '__name__': '__main__', '__spec__': None, 'x': 3} {}
{'foo': <function foo at 0x021C3468>, '__package__': None, '__builtins__': <module 'builtins' (built-in)>, '__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__doc__': None, '__name__': '__main__', '__spec__': None, 'x': 3} {'x': 4}
>>> def goo():
...     print(globals(), locals())
...     x = x + 1
...     print(globals(), locals())
...
>>> goo()
{'foo': <function foo at 0x021C3468>, '__package__': None, '__builtins__': <module 'builtins' (built-in)>, '__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__doc__': None, '__name__': '__main__', '__spec__': None, 'goo': <function goo at 0x021C3420>, 'x': 3} {}
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 3, in goo
UnboundLocalError: local variable 'x' referenced before assignment
>>>

Can't figure out what makes it different:-(

--Jach